Britain and France must work together to protect the international order, French President Emmanuel Macron said in an address to the British parliament on Tuesday.

The French leader was welcomed to Britain by King Charles on Tuesday for the first state visit by a European leader since Brexit, their warm greeting symbolising the return of closer ties between the two countries.

During his speech to parliament, Macron said Europe would never abandon Ukraine, adding that Britain and France will work with the "coalition of the willing" until the last minute to secure a ceasefire.

While Macron's three-day trip is filled with talks on economic issues and foreign affairs, the first day of the state visit, which comes 16 years after the late Queen Elizabeth hosted then French president Nicolas Sarkozy, has been largely focused on pageantry, and heavy in symbolism.

Macron is due to head back to Windsor Castle for the state dinner, where he and the king will speak before some 150 guests. (Reuters)